A manifesto opens John R. Stilgoe's new book, Outside Lies Magic. Thoreau would have been proud of it: "Get out now. Not just outside, but beyond the trap of the programmed electronic age so gently closing around so many people at the end of our century. Go outside, move deliberately, then relax, slow down, look around. Do not jog. Do not run . . . Walk. Stroll. Saunter . . . Explore."...